add uuid version 6 and 7 (#139)

* add uuid version 6 and 7

* fix comment

Author: it512

Diff for: time.go

@@ -108,12 +108,23 @@ func setClockSequence(seq int) {
 }
 
 // Time returns the time in 100s of nanoseconds since 15 Oct 1582 encoded in
-// uuid.  The time is only defined for version 1 and 2 UUIDs.
+// uuid.  The time is only defined for version 1, 2, 6 and 7 UUIDs.
 func (uuid UUID) Time() Time {
-	time := int64(binary.BigEndian.Uint32(uuid[0:4]))
-	time |= int64(binary.BigEndian.Uint16(uuid[4:6])) << 32
-	time |= int64(binary.BigEndian.Uint16(uuid[6:8])&0xfff) << 48
-	return Time(time)
+	var t Time
+	switch uuid.Version() {
+	case 6:
+		time := binary.BigEndian.Uint64(uuid[:8]) // Ignore uuid[6] version b0110
+		t = Time(time)
+	case 7:
+		time := binary.BigEndian.Uint64(uuid[:8])
+		t = Time((time>>16)*10000 + g1582ns100)
+	default: // forward compatible
+		time := int64(binary.BigEndian.Uint32(uuid[0:4]))
+		time |= int64(binary.BigEndian.Uint16(uuid[4:6])) << 32
+		time |= int64(binary.BigEndian.Uint16(uuid[6:8])&0xfff) << 48
+		t = Time(time)
+	}
+	return t
 }
 
 // ClockSequence returns the clock sequence encoded in uuid.

Diff for: uuid_test.go

@@ -73,6 +73,9 @@ var tests = []test{
 	{"f47ac10b58cc037285670e02b2c3d479", 0, RFC4122, true},
 	{"f47ac10b58cc037285670e02b2c3d4790", 0, Invalid, false},
 	{"f47ac10b58cc037285670e02b2c3d47", 0, Invalid, false},
+
+	{"01ee836c-e7c9-619d-929a-525400475911", 6, RFC4122, true},
+	{"018bd12c-58b0-7683-8a5b-8752d0e86651", 7, RFC4122, true},
 }
 
 var constants = []struct {
@@ -748,3 +751,114 @@ func BenchmarkUUIDs_Strings(b *testing.B) {
 		uuids.Strings()
 	}
 }
+
+func TestVersion6(t *testing.T) {
+	uuid1, err := NewV6()
+	if err != nil {
+		t.Fatalf("could not create UUID: %v", err)
+	}
+	uuid2, err := NewV6()
+	if err != nil {
+		t.Fatalf("could not create UUID: %v", err)
+	}
+
+	if uuid1 == uuid2 {
+		t.Errorf("%s:duplicate uuid", uuid1)
+	}
+	if v := uuid1.Version(); v != 6 {
+		t.Errorf("%s: version %s expected 6", uuid1, v)
+	}
+	if v := uuid2.Version(); v != 6 {
+		t.Errorf("%s: version %s expected 6", uuid2, v)
+	}
+	n1 := uuid1.NodeID()
+	n2 := uuid2.NodeID()
+	if !bytes.Equal(n1, n2) {
+		t.Errorf("Different nodes %x != %x", n1, n2)
+	}
+	t1 := uuid1.Time()
+	t2 := uuid2.Time()
+	q1 := uuid1.ClockSequence()
+	q2 := uuid2.ClockSequence()
+
+	switch {
+	case t1 == t2 && q1 == q2:
+		t.Error("time stopped")
+	case t1 > t2 && q1 == q2:
+		t.Error("time reversed")
+	case t1 < t2 && q1 != q2:
+		t.Error("clock sequence changed unexpectedly")
+	}
+}
+
+// uuid v7 time is only unix milliseconds, so
+// uuid1.Time() == uuid2.Time() is right, but uuid1 must != uuid2
+func TestVersion7(t *testing.T) {
+	SetRand(nil)
+	m := make(map[string]bool)
+	for x := 1; x < 32; x++ {
+		uuid, err := NewV7()
+		if err != nil {
+			t.Fatalf("could not create UUID: %v", err)
+		}
+		s := uuid.String()
+		if m[s] {
+			t.Errorf("NewV7 returned duplicated UUID %s", s)
+		}
+		m[s] = true
+		if v := uuid.Version(); v != 7 {
+			t.Errorf("UUID of version %s", v)
+		}
+		if uuid.Variant() != RFC4122 {
+			t.Errorf("UUID is variant %d", uuid.Variant())
+		}
+	}
+}
+
+// uuid v7 time is only unix milliseconds, so
+// uuid1.Time() == uuid2.Time() is right, but uuid1 must != uuid2
+func TestVersion7_pooled(t *testing.T) {
+	SetRand(nil)
+	EnableRandPool()
+	defer DisableRandPool()
+
+	m := make(map[string]bool)
+	for x := 1; x < 128; x++ {
+		uuid, err := NewV7()
+		if err != nil {
+			t.Fatalf("could not create UUID: %v", err)
+		}
+		s := uuid.String()
+		if m[s] {
+			t.Errorf("NewV7 returned duplicated UUID %s", s)
+		}
+		m[s] = true
+		if v := uuid.Version(); v != 7 {
+			t.Errorf("UUID of version %s", v)
+		}
+		if uuid.Variant() != RFC4122 {
+			t.Errorf("UUID is variant %d", uuid.Variant())
+		}
+	}
+}
+
+func TestVersion7FromReader(t *testing.T) {
+	myString := "8059ddhdle77cb52"
+	r := bytes.NewReader([]byte(myString))
+	r2 := bytes.NewReader([]byte(myString))
+	uuid1, err := NewV7FromReader(r)
+	if err != nil {
+		t.Errorf("failed generating UUID from a reader")
+	}
+	_, err = NewV7FromReader(r)
+	if err == nil {
+		t.Errorf("expecting an error as reader has no more bytes. Got uuid. NewV7FromReader may not be using the provided reader")
+	}
+	uuid3, err := NewV7FromReader(r2)
+	if err != nil {
+		t.Errorf("failed generating UUID from a reader")
+	}
+	if uuid1 != uuid3 {
+		t.Errorf("expected duplicates, got %q and %q", uuid1, uuid3)
+	}
+}

Diff for: version6.go

@@ -0,0 +1,56 @@
+// Copyright 2023 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package uuid
+
+import "encoding/binary"
+
+// UUID version 6 is a field-compatible version of UUIDv1, reordered for improved DB locality.
+// It is expected that UUIDv6 will primarily be used in contexts where there are existing v1 UUIDs.
+// Systems that do not involve legacy UUIDv1 SHOULD consider using UUIDv7 instead.
+//
+// see https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format-03#uuidv6
+//
+// NewV6 returns a Version 6 UUID based on the current NodeID and clock
+// sequence, and the current time. If the NodeID has not been set by SetNodeID
+// or SetNodeInterface then it will be set automatically. If the NodeID cannot
+// be set NewV6 set NodeID is random bits automatically . If clock sequence has not been set by
+// SetClockSequence then it will be set automatically. If GetTime fails to
+// return the current NewV6 returns Nil and an error.
+func NewV6() (UUID, error) {
+	var uuid UUID
+	now, seq, err := GetTime()
+	if err != nil {
+		return uuid, err
+	}
+
+	/*
+	    0                   1                   2                   3
+	    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	   |                           time_high                           |
+	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	   |           time_mid            |      time_low_and_version     |
+	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	   |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
+	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	   |                         node (2-5)                            |
+	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	*/
+
+	binary.BigEndian.PutUint64(uuid[0:], uint64(now))
+	binary.BigEndian.PutUint16(uuid[8:], seq)
+
+	uuid[6] = 0x60 | (uuid[6] & 0x0F)
+	uuid[8] = 0x80 | (uuid[8] & 0x3F)
+
+	nodeMu.Lock()
+	if nodeID == zeroID {
+		setNodeInterface("")
+	}
+	copy(uuid[10:], nodeID[:])
+	nodeMu.Unlock()
+
+	return uuid, nil
+}

Diff for: version7.go

@@ -0,0 +1,75 @@
+// Copyright 2023 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package uuid
+
+import (
+	"io"
+)
+
+// UUID version 7 features a time-ordered value field derived from the widely
+// implemented and well known Unix Epoch timestamp source,
+// the number of milliseconds seconds since midnight 1 Jan 1970 UTC, leap seconds excluded.
+// As well as improved entropy characteristics over versions 1 or 6.
+//
+// see https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format-03#name-uuid-version-7
+//
+// Implementations SHOULD utilize UUID version 7 over UUID version 1 and 6 if possible.
+//
+// NewV7 returns a Version 7 UUID based on the current time(Unix Epoch).
+// Uses the randomness pool if it was enabled with EnableRandPool.
+// On error, NewV7 returns Nil and an error
+func NewV7() (UUID, error) {
+	uuid, err := NewRandom()
+	if err != nil {
+		return uuid, err
+	}
+	makeV7(uuid[:])
+	return uuid, nil
+}
+
+// NewV7FromReader returns a Version 7 UUID based on the current time(Unix Epoch).
+// it use NewRandomFromReader fill random bits.
+// On error, NewV7FromReader returns Nil and an error.
+func NewV7FromReader(r io.Reader) (UUID, error) {
+	uuid, err := NewRandomFromReader(r)
+	if err != nil {
+		return uuid, err
+	}
+
+	makeV7(uuid[:])
+	return uuid, nil
+}
+
+// makeV7 fill 48 bits time (uuid[0] - uuid[5]), set version b0111 (uuid[6])
+// uuid[8] already has the right version number (Variant is 10)
+// see function  NewV7 and NewV7FromReader
+func makeV7(uuid []byte) {
+	/*
+		 0                   1                   2                   3
+		 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+		|                           unix_ts_ms                          |
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+		|          unix_ts_ms           |  ver  |       rand_a          |
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+		|var|                        rand_b                             |
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+		|                            rand_b                             |
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	*/
+	_ = uuid[15] // bounds check
+
+	t := timeNow().UnixMilli()
+
+	uuid[0] = byte(t >> 40)
+	uuid[1] = byte(t >> 32)
+	uuid[2] = byte(t >> 24)
+	uuid[3] = byte(t >> 16)
+	uuid[4] = byte(t >> 8)
+	uuid[5] = byte(t)
+
+	uuid[6] = 0x70 | (uuid[6] & 0x0F)
+	// uuid[8] has already has right version
+}